US3663683A - Polyester heat relax processes - Google Patents

Polyester heat relax processes Download PDF

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Publication number
US3663683A
US3663683A US840252A US3663683DA US3663683A US 3663683 A US3663683 A US 3663683A US 840252 A US840252 A US 840252A US 3663683D A US3663683D A US 3663683DA US 3663683 A US3663683 A US 3663683A
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Prior art keywords
film
heat
section
relax
temperatures
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Expired - Lifetime
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US840252A
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English (en)
Inventor
Alfred E Czerkas
Roger B Kenyon
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Eastman Kodak Co
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Eastman Kodak Co
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C53/00—Shaping by bending, folding, twisting, straightening or flattening; Apparatus therefor
    • B29C53/16—Straightening or flattening
    • B29C53/18—Straightening or flattening of plates or sheets

Definitions

  • the present invention relates to the processing of poly- (ethylene terephthalate) film to improve its planarity and to significantly shorten the time required to manufacture oriented, heat set, heat relaxed poly(ethylene terephthalate) films.
  • Films that can be directionally oriented and heat set such as poly(ethylene terephthalate) are also conventionally subjected to a special heat treatment (subsequent to the heat set treatment), known in the art as a heat relax treatment or step.
  • a heat relax treatment differentiated from a heat set treatment by the fact that, while considerable tension is applied to the film during the heat set operation (such that the dimensions of the film are held substantially constant during the heat set treatment), the film is maintained under only a slight tension during the subsequent heat relax step (see, for example, details in US. Pat. 2,779,684).
  • the use of a heat relax step in such overall continuous processes results in a still further improvement in the dimensional stability of the finished film.
  • This subsequent heat treatment (i.e., subsequent to the heat set operation) is also conventionally followed immediately by a cooling treatment, whereby the film is moved through a cooling section in order to fairly quickly lower its temperature to below the second order transition temperature of the film, so that the film is then in a condition suitable for further handling, including the wind ing of it onto rolls.
  • a heat relaxing step (involving heating the film under, at most, only slight tension at a temperature slightly above the softening temperature of the film to improve its dimensional stability)
  • a subsequent cooling step whereby the temperature of the film is lowered to below its softening temperature fairly quickly).
  • the sections Will herein be termed, respectively, the heat relax section (or heat relax air section) and the cooling sec tion (or cooling air section) in the order in which the film is passed through these sections during its manufacture.
  • the heat relax section occupies a large portion of the total machine space because it has been found necessary to expose the film at temperatures of up to about 280 F. for a fairly long period of time in order to obtain the desired degree of heat relax.
  • the film requires about 3 /2 minutes to pass through the heat relax section.
  • the film traverses a total of about 350 feet during its passage through the heat relax section.
  • temperatures of 300 F. or higher in the heat relax section of polyester processes because each time the temperature is raised to 300 F.
  • the temperature of the atmosphere in the heat relax section must be maintained within the range of from about 300 C. to about 350 F. [Such Very high temperatures were heretofer believed not pratical for use in the heat relax section because in this temperature region films of poly(ethylene terephthalate) soften to a considerably greater degree than they do at temperatures below 300 F.]
  • FIG. 1 is a schematic view showing a conventional prior art film path used in the final heat relax and cooling sections of a polyester film making machine
  • FIG. 2 is a schematic view similar to FIG. 1 and showing the film path modified according to one of the preferred embodiments of the present invention.
  • the processes of the present invention are accomplished by supporting the film during its traversal through the extremely hot (300 F.350 F.) heat relax section in such a way that there is no unsupported span of film which is over about 15 inches in length.
  • the unsupported film span should be at most about inches.
  • the supports for the film which may take the form of idler rolls, and the like, extend transversely entirely across the width of the film.
  • FIG. 1 there is schematically shown a conventional prior art roll arrangement for supporting a polyester film F as it is transported through the final heat treatment air section '10 and into the suceeding cooling air section 11, the two sections being separated by a partition 12.
  • the film F before entering these last two treating sections 10 and 11 may have been oriented longitudinally, laterally, or both, before or after having been coated with a suitable substrate and heat treated one or more times to improve the dimensional stability of the film, dry the applied substrata, etc. by any suitable means well known in the art, and not shown.
  • each of the heat treatment air section 10 and the cooling air section .11 is suitably enclosed so that the desired temperature conditions can be maintained therein upon being obtained by suitable means, not shown.
  • the entering film F is guided and supported in an undulating path by a series of upper idler rolls 13 and lower idler rolls 13'.
  • the idler rolls 13 and 13" extend completely across the film path to engage the full width of the film and are rotatably supported at opposite ends in pairs of upper and lower support bars 14 and 14, respectively, extending along opposite sides of the section.
  • the film Upon leaving the heat relax section 10 the film passes under partition 12 and over idler roller 15' where it is redirected vertically upward through the cooling air section 11 and over upper guide rolls 15. As the film moves upwardly upon entering the cooling air section 11, it passes between two air plenums which are provided along their length with openings, not shown, through which streams of cool air issue and impinge upon the full width of the film as indicated at 21.
  • the upper and lower idler or guide rolls in both the heat relax and cooling sections have been spaced apart by 6 feet to 8 feet so that the unsupported film spans in these sections have been 6 to 8 feet in length.
  • temperature to which the film is subjected in the heat treatment section 10 may range from about 150 F. to about 290 F. depending upon the type of treatment the film has received prior to reaching this final heat treatment stage.
  • the prior art film making machine shown in FIG. 1 can be modified as shown in FIG. 2 where corresponding parts are identified by the same reference characteristics.
  • the film is passed back and forth around a series of closely spaced idler rolls during its passage through the heat relax section (where temperatures of 300 F.350 F. are maintained).
  • the closely spaced idler rolls can also be continued in at least the beginning of the cooling section.
  • the film is passed back and forth over a plurality of closely spaced idler rolls vertically spaced in ladder fashion along one or more supports 26.
  • the film in cooling section 11 is passed upwardly back and forth over a series of closely spaced idler rolls 27. It is preferred that the lowermost guide roll 25 in the heat section and the lowermost guide roll 27 in the cooling section should be so spaced with the idler rolls, so that the unsupported span between any of them is at most about 10 inches, also.
  • the temperatures maintained in the heating section 10 during the practice of the present invention may vary from about 300 F. to about 350 F. depending somewhat upon the treatment which the film has received prior to passing through the heat relax section, and upon the speed with which the film traverses the heat relax section.
  • the length of the film path in the heat relax section 10 must be sufficiently short to permit passage of the film through the heat relax section in at most about 10 seconds (generally quicker when preferred temperatures of from about 320 to about 350 F. are used).
  • the actual maximum length of the film path through the heating section will, of course, depend largely upon the rate of film travel through the machine. Thus, when speeds of feet per minute are used, for example, the maximum film path should be only about 20 feet in the zone where exposure to atmospheres at temperatures of 300 F. or more takes place.
  • thermoplastic poly(ethylene terephthalate) film which process comprises, in a heat relaxing step, passing oriented, heat stabilized, unrelaxed poly(ethylene terephthalate) film under only slight tension through a heated section in which the temperature of said film is maintained above its second order transition temperature to thereby at least partially heat relax said oriented film; the improvement which comprises (a) maintaining the temperature of the hot atmosphere in said heated section between about 300 F.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
  • Shaping By String And By Release Of Stress In Plastics And The Like (AREA)
US840252A 1969-07-09 1969-07-09 Polyester heat relax processes Expired - Lifetime US3663683A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US84025269A 1969-07-09 1969-07-09

Publications (1)

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US3663683A true US3663683A (en) 1972-05-16

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US840252A Expired - Lifetime US3663683A (en) 1969-07-09 1969-07-09 Polyester heat relax processes

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US (1) US3663683A (enrdf_load_stackoverflow)
FR (1) FR2054261A5 (enrdf_load_stackoverflow)
GB (1) GB1306125A (enrdf_load_stackoverflow)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4140740A (en) * 1976-04-15 1979-02-20 Agfa-Gevaert N.V. Flatness control of thermoplastic film
US4141735A (en) * 1975-03-31 1979-02-27 Eastman Kodak Company Process for reducing core-set curling tendency and core-set curl of polymeric film elements
US4275107A (en) * 1980-05-19 1981-06-23 International Business Machines Corporation Polyester stabilization process and product
US5407625A (en) * 1993-11-22 1995-04-18 Wellman, Inc. Method of forming self-texturing filaments and resulting self-texturing filaments
US5445779A (en) * 1994-01-14 1995-08-29 The Dow Chemical Company Process for the drying and heat-treatment of polybenzazole films
US5531951A (en) * 1993-11-22 1996-07-02 Wellman, Inc. Method of forming staple fibers from self-texturing filaments
US6235458B1 (en) 1997-08-01 2001-05-22 Fuji Photo Film Co., Ltd. Photographic film and heat-treatment method thereof
CN101002110B (zh) * 2004-08-10 2010-12-08 佳能株式会社 放射线探测装置、闪烁体板及其制造方法和放射线探测系统

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3539500A1 (de) * 1985-11-07 1987-05-14 Hoechst Ag Verfahren und vorrichtung zur verminderung von ungleichmaessigkeiten und zur dimensionsstabilisierung von thermoplastischen folienbahnen

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4141735A (en) * 1975-03-31 1979-02-27 Eastman Kodak Company Process for reducing core-set curling tendency and core-set curl of polymeric film elements
US4140740A (en) * 1976-04-15 1979-02-20 Agfa-Gevaert N.V. Flatness control of thermoplastic film
US4275107A (en) * 1980-05-19 1981-06-23 International Business Machines Corporation Polyester stabilization process and product
US5407625A (en) * 1993-11-22 1995-04-18 Wellman, Inc. Method of forming self-texturing filaments and resulting self-texturing filaments
US5510183A (en) * 1993-11-22 1996-04-23 Wellman, Inc. Method of forming self-texturing filaments and resulting self-texturing filaments
US5531951A (en) * 1993-11-22 1996-07-02 Wellman, Inc. Method of forming staple fibers from self-texturing filaments
US5614296A (en) * 1993-11-22 1997-03-25 Wellman, Inc. Resilient molded preform made from staple fibers of self-texturing filaments
US5445779A (en) * 1994-01-14 1995-08-29 The Dow Chemical Company Process for the drying and heat-treatment of polybenzazole films
US6235458B1 (en) 1997-08-01 2001-05-22 Fuji Photo Film Co., Ltd. Photographic film and heat-treatment method thereof
CN101002110B (zh) * 2004-08-10 2010-12-08 佳能株式会社 放射线探测装置、闪烁体板及其制造方法和放射线探测系统

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Publication number Publication date
GB1306125A (enrdf_load_stackoverflow) 1973-02-07
FR2054261A5 (enrdf_load_stackoverflow) 1971-04-16

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